A:蛋白质
B:糖类
C:水
D:无机盐
补全对话, 其中有两个多余选项。
A: Hello! This is Tom speaking. ____
B: Sorry, Jack is out at the moment.
A: ____
B: This is Jack’s mother.
A: Hello! Mrs Brown. ____
B: Of course. ____
A: That’s very kind of you. Would you please tell Jack we will have a party about stamp collection this Sunday morning?
B: Oh, a party about stamp collection on Sunday morning. OK, ____
A. Who's speaking, please?
B. Hold the line, please.
C. Can you take a message for me?
D. Can I take a message for you?
E. I'll tell him as soon as he comes back.
F. Could I speak to Joe, please?
G. Could I speak to Jack, please?
如图,在平面直角坐标系xOy中,A(2,0),B(0,2),⊙C的圆心为点C(-1,0),半径为1.若D是⊙C上的一个动点,线段DA与y轴交于点E,则△ABE面积的最大值是
在实数中2,0,﹣4,1,﹣2,最大的实数是( )